The present invention pertains to an emergency lighting system that is battery operated and particularly one which is completely self-contained and is maintenance-free.
A variety of emergency lighting systems have been known in the prior art and fundamentally these systems insure that if a source of AC power which provides the normal or regular lighting for a given environment should for any reason fail, emergency lighting is furnished. Generally what this involves is an automatic switching over from the normal or regular AC supply to an encased battery supply which furnishes the needed current to an emergency lamp.
The difficulty with the design and construction of most prior art emergency lighting systems is that they do not lend themselves to the prevention of vandalism. Thus, when the emergency systems of the prior art are left unattended, they can become easily disabled by reason of tampering with switches or other mechanisms or because of breakage of important elements such as the cover of the lighting unit. As a result, such emergency lighting systems must be frequently checked to determine if any tampering has occurred.
Accordingly, it is a primary object of the present invention to provide an emergency lighting system or device that is completely self-contained so as to preclude any substantial interference with the availability of the lighting system when called for.
It is another object of the present invention to provide for a simple, inexpensive effective means for testing of the system to determine that it is operating correctly and that the emergency lamp will be energized if the AC power should be cut off.
A further object is to accomplish the testing from the outside of the emergency lighting unit while the actual test switch is fully protected.
In accordance with the objects noted above, a primary feature of the present invention resides in the provision of a magnetically operated test switch suitably connected in the electrical circuitry and located inside the housing of the emergency lighting device. All that is required is that the operator bring a suitably configured magnet close to the cover of the unit or device and to thereby cause appropriate operation of contacts within the housing so as to effectively open the AC power supply and thereby to switch in the battery supply which furnishes current to the emergency lamp.
Another primary feature of the present invention is concerned with the protection of the emergency lamp from any kind of repeated shocks to the cover or housing. To this end it is provided that the lamp floats within the housing and this is achieved by having flexible mounting of the reflector platform to which the circuitry is affixed, and also flexible connection of the printed circuit board holding the circuitry to the reflector platform.
Yet another feature of the present invention resides in a special arrangement of the cover and of a tamper-proof screw used to attach the cover to the base plate of the emergency lighting device or unit. The cover is provided with a skirt portion that encloses the perimeter of the base plate, the latter being directly mounted to a wall or ceiling. The skirt portion prevents access to the mounting screws that are used to effect the mounting or attachment of the base plate. The tamper-proof screw holds the cover in engagement with the base plate but such screw can only be loosened by having the appropriate tool.
A further feature of the invention concerns an advancement over prior art emergency lighting units which include a normally closed relay, that is, a relay whose contacts are closed when the associated coil is de-energized. Thus, when AC power is on, the relay contacts are open but such contacts close and connect the light source to the battery supply when the AC power fails. Unlike these prior art units, the emergency lighting device of the present invention utilizes a normally open relay, that is, one which is energized only during AC power failure. Thus the relay is not operative, is not consuming energy and is not therefore losing life during extended periods of AC operation.
Other and further objects, advantages and features of the present invention will be understood by reference to the following specification in conjunction with the annexed drawing, wherein like parts have been given like numbers.